The invention relates generally to alignment systems for spherical-shaped objects, and more particularly, to a method and system for aligning and handling spherical-shaped objects suitable for use in the manufacture and transport of spherical-shaped semiconductor integrated circuits.
Conventional integrated circuits, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
A fabrication facility is relatively expensive due to the enormous effort and expense required for creating flat silicon wafers and chips. For example, manufacturing the wafers requires several high-precision steps including creating rod-form polycrystalline semiconductor material; precisely cutting ingots from the semiconductor rods; cleaning and drying the cut ingots; manufacturing a large single crystal from the ingots by melting them in a quartz crucible; grinding, etching, and cleaning the surface of the crystal; cutting, lapping and polishing wafers from the crystal; and heat processing the wafers. Moreover, the wafers produced by the above processes typically have many defects which are largely attributable to the difficulty in making a single, highly pure crystal due to the above cutting, grinding and cleaning processes as well as due to the impurities, including oxygen, associated with containers used in forming the crystals. These defects become more and more prevalent as the integrated circuits formed on these wafers become smaller.
Another major problem associated with modern fabrication facilities for flat chips is that they require extensive and expensive equipment. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting and warping. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, because the wafers are round and the completed chips are rectangular, the peripheral portion of each wafer cannot be used.
Another problem associated with modern fabrication facilities is that they do not produce chips that are ready to use. Instead, there are many additional steps that must be completed, including cutting and separating the chip from the wafer; assembling the chip to a lead frame which includes wire bonding, plastic or ceramic molding and cutting and forming the leads, positioning the assembled chip onto a printed circuit board; and mounting the assembled chip to the printed circuit board. The cutting and assembly steps introduce many errors and defects due to the precise requirements of such operations. In addition, the positioning and mounting steps are naturally two-dimensional in character, and therefore do not support curved or three dimensional areas. Therefore, due to these and various other problems, only a few companies in the world today can successfully manufacture conventional flat chips. Furthermore, the chips must bear a high price to cover the costs of manufacturing, as well as the return on initial capital and investment.
In U.S. Pat. No. 5,955,776 (Ishikawa), assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and system for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. As disclosed in the aforementioned patent application, the manufacturing process by which a spherical-shaped semiconductor integrated circuit is produced may include a variety of processing steps. Among these are: deposition of films, and photo-lithography.
Complicating the manufacturing process for spherical-shaped semiconductor integrated circuits are the special handling requirements which must be afforded the circuits during their manufacture. Unlike conventional integrated circuits formed from flat surface semiconductor wafers, the spherical-shaped semiconductor integrated circuits produced from spherical-shaped semiconductors consume the entire surface area of the spherical-shaped semiconductors. Also, unlike conventional integrated circuits which may be grasped along bottom or side surfaces thereof, grasping or otherwise contacting spherical-shaped semiconductor during the manufacturing process may result in significant damage thereto. Furthermore, many of the processing techniques used to manufacture conventional integrated circuits are unsuitable for use in the manufacture of spherical-shaped semiconductor integrated circuits.
Further complicating the manufacturing process for spherical-shaped semiconductor integrated circuits is the ability to align each device, such as is required in photolithographic processes. Unlike conventional semiconductor wafers that can be placed on a chuck and aligned with alignment marks thereon inscribed, the spherical-shaped semiconductor integrated circuit devices can move and roll on a chuck. Also, unlike conventional semiconductor devices that can have their entire surface exposed to a single alignment camera, the spherical-shaped semiconductor integrated circuit devices typically conceal at least one-half of its surface area from an alignment camera.
Therefore, the difficulties associated with the handling and alignment of spherical-shaped semiconductor integrated circuits during the manufacturing process remains an obstacle to the development of such devices.
While the contactless capture of spherical objects using a diverging nozzle has been disclosed in U.S. Pat. No. 6,048,011 (Ser. No. 09/162,616) to Fruhling et al., aligning the spherical shaped object has not yet been achieved. The nozzle disclosed in Fruhling et al. may be used, however, in some capacity to facilitate alignment.
Thus, there remains a need for a system and method capable of readily capturing, holding and aligning spherical-shaped objects.